How Much Does a House Extension Cost?

How much does a home extension cost? As with any build, it comes down to a number of factors. However, the size and quality of the extension are going to be the deciding cost factors.

Typically, house extension prices will start from £1,000 per m2 to £1,500 per square metre.

For example, a 20m squared extension that is 4m x 5m can cost anything from £22,000 to £28,000.

A basic single-storey extension might start at around £1,200 per square metre.

Of course, prices will reflect the type of materials used, the complexity of design and where you live in the UK.

A home extension can be a big financial investment so it’s important you put thought into how much your house extensions costs.

Other Extension Cost Factors

Prices will cover the essential elements of the build. This includes constructing the foundations, building the walls, insulating and plumbing and electrics.

• Labour
• Foundations and footings
• Plastering
• Structural Openings
• Brickwork
• Electrics and plumbing
• Internal Decoration

Expect to add on 10 -15% for professional fees:

• Architects
• Planning Permission
• Building Regulation
• Structural Engineer

You will also have to consider VAT. Your home extension cost could go from £40,000 to £60,0000.

Most builders will be able to give you an idea of how much your extension will cost per square foot or metre. The average cost should cover design through to decorating but it’s worth having a back-up just in case. Think about having a 10-15% contingency in case of unexpected costs.

Building Site Constraints

You will have to factor in additional costs about your site. If you have a complex site, you’ll need to ask your builder to factor in extra costs such as:

Soil type – do you have a specific type that demands a certain technique or material?

Changes to the existing structure – any changes to steel work or walls?

Ease of access – will any drainage, pipework or gas meters need to be moved?

House Extension Quotation Breakdown

House Extension Cost Calculator

Use our free house extension cost calculator for instant, online guide prices. It’s free, simply to use and gives you an extension cost within minutes.

How Can I Extend My House Cheaply?

Home extensions can vary greatly. In shape, size and therefore budget – this is why the answer is never straightforward one.

You will have to first decide how much you are willing to spend. This may come down to a matter of resources, aspirations and reality checks.

However, there are many ways you can cut extension costs and extend your home cheaply. Taking the time planning the smallest of details can help you save money down the line.

Everything from light fittings to socket locations and flooring need to be considered. Plan these well from the outset and you’ll save on alterations at a later stage.

There are many ways you can fund our extension project. Ideally, you would use any savings you have but in reality, this isn’t always viable.

You can always take out a personal loan but you will need to factor in the interest that you will be paying.

Re-Think The Design

It’s good to know exactly what you want from your extension at an early stage. Is your design the best use of space?

Rather than re-thinking your budget, you will want to take another look at your plans and extension design. Simplifying the design can help shave a bit of money off your project.

You might want to hire a professional to help you with this. Cutting certain elements of the design could ruin the look or function of your space. You don’t want to have budget versus profit.

Curves and corners can be costly to build. A rectangular or square footprint with a simple pitched roof will be much more affordable. It won’t compromise the builds quality either.

Stick To It

Once you have the design carefully planned out, it’s important that you do your best to stick to it. Any changes will cost money. Ensure you have a building contract with an itemised budget and an order of works in place.

Any project has the potential to yield a nasty surprise, as well as temptation to upscale. This is why you must draw up a robust budget and stick to it as best you can.

Get The Timing Right

Time your extension carefully. Bad weather can cause delays, and this means increased labour costs and rejigged schedules. This something that will need to be thought about, especially if you plan on renting while you extend.

Damage from wind and rain can up your costs too. A simple extension can become a complete redecoration job if rain penetrates tarpaulins.

Spring or the Summer period is usually the best time to extend, or when prolonged periods of dry weather is expected.

For example, Summer is the ideal time to plan an extension. This allows you to get quotes in the Autumn, ready to go for Spring.

Avoid Complicated Groundworks

You will want to try and avoid complicated groundworks where possible. Avoid building too close to trees, drains and sewers as this will increase groundwork costs.